Luminar 4 is an award winning software package developed by Skylum. At the time of writing Luminar 4 was the current version but a new version Luminar AI, with even more AI tools is soon to be released (writing in Dec 2020). It works as a standalone application or as a plugin for Photoshop and Lightroom. It handles RAW images adeptly and has powerful tonal adjustment controls that can be applied globally or locally. It comes packaged with a range of AI tools offering things like automated image enhancement and automated sky replacement.
Its underlying paradigm is of nondestructive editing using of layers and masks. You can add separate image layers, so you can make composite images with ease, and you can apply variable transparency, masking and a range of blending modes to each layer.
Luminar has a useful Help menu that links to a vast resource of guides and tutorials on their website.
Luminar has file management built in, but this (afaik) is much less powerful than what Lightroom offers. It gives a file browser, and a non-heirarchical facility for “albums” that you can use to make logical collections of images. I couldn’t see any management for keywording etc.
File can be exported to the usual output formats, but the export dialog is very basic.
You can find more about Luminar at the maker’s sites hyperlinked in the first paragraph, or do a web search to find extensive documentation and reviews.